In recent years, research and development of dye-sensitized photovoltaic cells, in which a dye is used as a photosensitizing agent, is under way. A conventional dye-sensitized photovoltaic cell typically includes a photoanode containing a dye, a counter electrode, an electron transport layer and a hole transport layer provided between the photoanode and the counter electrode, and an electrolyte solution containing a redox pair. In order to improve the characteristics of a dye-sensitized photovoltaic cell, improvements in the characteristics of the respective component elements are needed.
Patent Document 1 discloses a photoelectric conversion element whose hole transport characteristics are improved by using as a hole transport layer a gel layer which contains an organic compound including an oxidation-reduction site. In the photoelectric conversion element of Patent Document 1, a gel layer containing an organic compound is also used as an electron transport layer.
Patent Document 2 discloses an energy-storable dye-sensitized photovoltaic cell having an electrical storage function. The energy-storable dye-sensitized photovoltaic cell described in Patent Document 2 includes a cell portion in which a photoelectrode and a counter electrode are disposed within a first electrolyte solution, and a battery portion which is partitioned from this cell portion by a cation exchange membrane and in which a charge storage electrode is disposed within a second electrolyte solution. The second electrolyte solution has the same cation species as that of the first electrolyte solution and a different anion species from that of the first electrolyte solution. The first electrolyte solution contains an oxidation-reduction substance (I−/I3−), and the cation exchange membrane is provided in order to prevent the oxidation-reduction substance from moving into the second electrolyte solution.